Apparatus for making precise dental castings



Aug. 2o, 1935. D w PHjLLlPS 2,011,649

`APPARATUS FOR MKING PRECISE DENTAL CASTINGS Original Filed Dec. l0, 1932 Patented Aug. 20, 1935 UNITED STATES PATENT OFFICE Arrmrus son MAKING rmtclsn DENTAL CASTINGS David W. Phillips, Chicago, lll.

7Clalms.

invention relates to scales and volumetric apparatus and more particularly it re- Illes to scales and measuring apparatus adjustxable to automatically weigh or measure out dif- 5 ferent portions or ingredients oi an admixture.

The'scale is adapted for a variety of uses and among others for correctly proportioning ingredi- 'cnts of admixtures used in practicing the method set -i'orth in my co-pending application, Serial 10 "Nbs 646,673, led December 10, 1932, 01 which this isa divisional application. My aforesaid application covers a novel method oi regulating the expansion of investment material used in makiliggdental castings, such investment material comprising as its a. high expansion 'accordance with the room temperature to effect exact compensation for the resulting shrinkage variar-lcs at diirerent investing room temperatures. The invention contemplates the provision o! apparatus adapted for precisely propor- `tloriing the mterialsused in the investing admixture although it may be used for other than investing admixtures.`

VAn object of the invention is the provision of improved apparatus adapted to automatically proportion the ingredients of an admixture in accordance with a predetermined schedule of temperatures.

Another object of the invention is the provision of improved weighing and measuring appa- .ratus adapted for precisely proportioning original investment material and control powder constituents o! an admixtureoi the kind described for investing at any prevailing room temperature in order that the admixture will provide the necessary quantity for one invemng operation and that the expansion ot the resulting investmimi: admixture will provide the proper balance :arles at theprevailing room temperayMany other objects and advantages of the conherein shown and described will be obvioustothose skilled'mtheartiromthedisclosure herein given.

To this end, my invention consists in the novel construction, tand combination of partsfherein described and shown, and more parn-tlciilsarly'pointed out Tin the claims. Ih the'drawing; wherein Eke reference charac- Fig. 1 is a plan view of a novel and improved weighing apparatus found satisfactory for properly proportioning admixtures at any prevailing room temperature;

Fig. 2 is an elevational view of the device shown in Fig. l;

Fig. 3 is a section along the line 3 3 of Fig. 1; and

Fig. 4 is a view of a measuring flask especially adapted for properly proportioning of the admixture by volume.

Referring now more particularly to the drawing, Figs. 1, 2 and 3 illustrate a. scale which is adjustable to automatically proportion the correct amount of both original investment material and control powder required for investing at any particular prevailing room temperature and which at the same time, provides the proper total amount of the admixture for one investing operation. This is accomplished without the use of any counterbalance weights and if desired with only one weighing receptacle which can be used for each material, the scale being of such weight and dimensions that it provides in itself the necessary counterbalance as the fulcrum points are changed in accordance with different prevailing room temperatures in weighing out either the original investment material or the control powder.

The following proportions and weights exemplify the amounts of original investment material and control powder found effective for practical work at room temperatures indicated. although satisfactory results are obtained by slight devia- Ihe scale is adapted to weigh out the exact quantities set forth in the above table and comprises a balancing arm I0 adapted to be pivotally supported at any one of a, plurality of fulcrum points, on a base member generally designated by the numeral Il, The arm I has an inverted U-shaped cross section over the greater portion of its length and terminates at its ends in annular or ring-shaped members i2 and i3 providing apertures Ill adapted to receive a cup or receptacle I5.

Thebalancing arm IG is adapted to be supported on the base member II at any of a plurality o notches I5 formed in the lower edge of the arm, with the upper edge of the base member Ii providing ay fulcrum. The notches i6 are arranged in two groups, each graduated from the left to the right as observed in Fig. 2 to indicate temperatures from 6i) degrees Fahrenheit to 110 degrees Fahrenheit, the left hand group being used as fulcrurn points in weighing out original investment material and the right hand group being used as iulcrum points in weighing out control powder.

The individual notches i6 comprising the right hand group are accurately positioned so that the exact amount oi control powder required for an investing operation at a room temperature indicated by the legends above the respective notches, will be weighed out when the scaie is balanced with the cup i5 containing the control powder positioned in the right hand receptacle it.

The arm id is shown as mounted on the member Ii with the upper edge of the latter in the particular notch I6 of the right hand group having the legend 50 degrees. By reference to the table, it will be seen that the original investment material provides the proper compensation for shrinkages when investing at a room temperature of 60 degrees so that no control powder is required. The cale is so constructed as to oe balanced in the position shown with the cup I5 empty. If the investing operation is to be performed at 65 degrees Fahrenheit, substantially ve grams of control powder will be required for one investing operation and this amount will be accurately weighed out by positioning the arm I il with the notch corresponding to 65 degrees Fahrenheit as a fulcrum point. The requisite amount of control powder for higher temperatures as indicated in the table will be provided by shifting the arm i8 so that its fulcrum point 'corresponds to the selected room temperature.

1n weighing out the original investment material at any selected room temperature, the arm I0 will be shifted so that the extreme left hand notch I6 receives the upper edge of the base member I I and the cup i5 is placed in the left hand aperture i4. The table indicates that 40 grams of original investment material and no control powder is required for an investing operation at a room temperature oi' 60 degrees. By pouring original investment material into the empty cup I5 until the scale is balanced, 40 grams of such material will be accurately weighed out. Similarly, for higher selected investing room temperatures, the arm will be shifted to the corresponding fulcrum points and the correspondingly lower weights of original investment material will be weighed out. Obviously, it makes no diiTerence whether the original investment material or the control powder is first weighed out, it being understood of course, that after weighing out one portion each of the control powder and of the original investment material, they will be mixed together and used for one investing operation.

The control powder selected as exemplifying the invention provides the required expansion compensation when investing at 110 degrees Fahrenheit without the use of any original investment material. It will be observed by reference to the table that grams of control powder provides a sufficient amount of investment material for one investing operation, and the scale is so constructed as to weigh out this amount when the arm is positioned with the member I I in the extreme right hand notch I6 and the cup I5 positioned in the right hand aperture I4. Similarly, since no original investment material is required at a temperature of 110 degrees, ifi4 the arm I0 is positioned with the member II in the leit hand notch IB having the legend 110 degrees and with the empty cup I5 positioned in the left hand aperture I4, the scale will be balanced.

Automatic volumetric proportioning of the described materials can also be effected by the device shown in Fig. 4, which consists of a transparent measuring cup I8 of suilicient capacity to hold the correct admixture of investment materials employed for one investing operation. The cup IB has selected room temperature graduations so arranged that when the original investment material is placed in the cup up to a graduation level corresponding to the selected room temperature,

and is then filled with control powder level with the top, the requisite proportions of both materials are provided to correctly regulate expansion in the admixture for the particular investing room temperature selected. For example, for a selected room temperature of degrees Fahrenheit, the cup I8 will be entirely filled with original investment material and no control powder will be contained in the investing admixture. By lling the cup with original investment material up to the level indicated at degrees Fahrenheit, and then by completing the lling of the cup with control powder, an admixture will be secured providing the proper compensation for expansion at a temperature of 65 degrees. An admixture of proper proportions for a selected room temperature of degrees will be eiected by lling the cup to the level indicated by the graduation 105 degrees and then lling the cup to the top with control powder. Likewise for a selected room temperature of degrees, no original investment material will be required and the cup I8 will be entirely iilled with control powder.

Having thus described the invention, it is obvious that various immaterial modications may be made in the same without departing from the invention; hence I do not wish to be .understood as limiting myself to the exact form, construction, arrangement and combination of parts herein shown and described, or uses mentioned.

What I claim as new and desire to secure by Letters Patent is:

l. A weighing device comprising a supporting member having its upper edge providing a fulcrum, an arm having a plurality of notches on its lower edge each adapted to receive said fulcrum, said notches being arranged in predetermined spaced apart relation in two groups, said groups being on opposite sides of the arm, means on each end of the arm adapted as a receptacle support, and areceptacle adapted for positioning on either of said supports, each of said notches comprising a group being marked with an indicating temperature diiering from that of the other notches of the same groups, the notches of each group placing the receptacle on that end of the arm "f5 and adding a selected material to the receptacle in an amount predetermined as required as an ingredient of an admixture used in investing at room temperature indicated at the selected fulcrum, the notches of the other group being so positioned that the arm will be balanced on the fulcrum at any selected notch by placing the receptacle on that end of the arm and adding a dierent selected material to the receptacle in an amount predetermined as required as an ingredient of said admixture.

2. Ina Weighing apparatus, a balancing arm providing an aperture at each end, a receptacle adapted to be interchangeably seated in either of said apertures, and a base member providing a knife edge support for the arm, each half of said arm having a plurality of notches in its lower edge arranged in spaced relation and adapted to receive the knife support, the notches on each half of the arm most remote from the adjacent aperture being so located as to adapt the arm to be balanced thereabout when the empty receptacle is seated in the adjacent aperture, the other notches on each half of the arm being so positioned that the weight of the material requisite to be added to the receptacle when seated in the adjacent aperture bears a denite and predetermined ratio to the weight of material requisite to balance the arm about a corresponding notch on the other half when the receptacle containing such material is seated in the aperture adjacent thereto.

3. A device of the kind described adapted to separately and selectively weigh out predetermined proportions of two ingredients of an admixture, said device comprising a base member providing a knife edge support, a balance arm having an aperture in each end and a plurality of notches in its lower edge, a receptacle adapted to be interchangeably seated in said apertures, the notches on one half of said arm being located at fulcrum points adapting the arm to be balanced thereabout when the receptacle is seated in the adjacent aperture and contains predetermined graduated quantities of one of said ingredients, the notches on the other half of the arm being located at fulcrum points adapting the arm to be balanced thereabout when the receptacle is seated in the adjacent aperture and contains predetermined graduated quantities of the other of said ingredients.

4. A device of the kind described adapted to separately and selectively weigh out predetermined proportions of two ingredients of an admixture, said device comprising a base member providing a knife edge support, a balance arm having an aperture in each end and a plurality of notches in its lower edge, a receptacle adapted to be interchangeably seated in said apertures, the notch adjacent the median line in each half of the arm being located at a fulcrum point adapting the arm to be balanced thereabout when the empty receptacle is seated in its adjacent aperture, and the remaining notches on each half of the arm each being located at a fulcrum point adapting the arm to be balanced thereabout when the receptacle is seated in the adjacent aperture and contains a predetermined quantity of one of said ingredients.

5. In a weighing apparatus, a balancing arm terminating at each end in a platform providing an aperture, a receptacle adapted to be seated in either of said apertures, and a base member providing a knife edge support shiftable longitudinally of the arm, the cross section of said arm between said platforms being an inverted U with its lower edges each providing a plurality o1' spaced-apart notches in alignment with corresponding notches in the other edge, one pair of aligned notches in each end of said arm being so positioned that the arm will be balanced thereabout when the empty receptacle is seated in the adjacent aperture.

6. In a weighing apparatus, a balancing arm terminating at each end in a platform providing an aperture, a receptacle adapted to be seated in either of said apertures, and a base member providing a knife edge support shiftable longitudinally of the arm, the cross section of said arm between said platforms being an inverted U with its lower edges each providing a plurality of spaced-apart notches in alignment with corresponding notches in the other edge, one pair of aligned notches in each end of said arm being so positioned that the arm will be balanced thereabout when the empty receptacle is seated in the adjacent aperture, and the remaining pairs of notches in each end of the arm being so positioned that the weight of material requisite to be added to the receptacle when seated in the adjacent aperture bears a definite and predetermined ratio to the weight of material requisite to similarly balance the arm about a corresponding pair of notches on the opposite end.

7. A device of the kind described adapted to separately weigh out predetermined proportions of two ingredients of an admixture graduated in accordance with existing room temperature, said device comprising a base member providing a knife edge support, a balance arm having an aperture in each end and a plurality oi.' notches on its lower edge, a receptacle adapted to be interchangeably seated in said apertures, the notch adjacent the median line on each half of the arm being located at a fulcrum point adapting the arm to be balanced thereabout when the empty receptacle is seated in its adjacent aperture, the remaining notches on each half of the arm each being located at a fulcrum point adapting the arm to be balanced thereabout when the receptacle is seated in the adjacent aperture and contains a predetermined quantity of one of said ingredients, the notches on both halves of the arm being successively and similarly graduated in the same direction for existing room temperatures within a selected range.

DAVID W. PHILLIPS. 

